Re: [PATCH 1/7] ttm/radeon/nouveau: Check the DMA address from TTM against known value.

[Pekka Paalanen <pq@iki.fi>]

On Tue, 30 Aug 2011 22:41:46 -0400
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:

> . instead of checking against the DMA_ERROR_CODE value which is
> per-platform specific. The zero value is a known invalid value
> that the TTM layer sets on the dma_address array if it is not
> used (ttm_tt_alloc_page_directory calls drm_calloc_large which
> creates a page with GFP_ZERO).
> 
> We can't use pci_dma_mapping_error as that is IOMMU
> specific (some check for a specific physical address, some
> for ranges, some just do a check against zero).
> 
> Also update the comments in the header about the true state
> of that parameter.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_sgdma.c |    3 +--
>  drivers/gpu/drm/radeon/radeon_gart.c    |    4 +---
>  include/drm/ttm/ttm_page_alloc.h        |    4 ++--
>  3 files changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_sgdma.c
> b/drivers/gpu/drm/nouveau/nouveau_sgdma.c index 82fad91..624e2db
> 100644 --- a/drivers/gpu/drm/nouveau/nouveau_sgdma.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
> @@ -42,8 +42,7 @@ nouveau_sgdma_populate(struct ttm_backend *be,
> unsigned long num_pages, 
>  	nvbe->nr_pages = 0;
>  	while (num_pages--) {
> -		/* this code path isn't called and is incorrect
> anyways */
> -		if (0) { /*dma_addrs[nvbe->nr_pages] !=
> DMA_ERROR_CODE)*/
> +		if (dev->pdev, dma_addrs[nvbe->nr_pages] != 0) {

This is weird, do you mean && instead of a comma, or what?
Or am I completely missing the comma operator semantics?

>  			nvbe->pages[nvbe->nr_pages] =
>  					dma_addrs[nvbe->nr_pages];
>  		 	nvbe->ttm_alloced[nvbe->nr_pages] =
> true; diff --git a/drivers/gpu/drm/radeon/radeon_gart.c
> b/drivers/gpu/drm/radeon/radeon_gart.c index a533f52..41f7e51
> 100644 --- a/drivers/gpu/drm/radeon/radeon_gart.c
> +++ b/drivers/gpu/drm/radeon/radeon_gart.c
> @@ -181,9 +181,7 @@ int radeon_gart_bind(struct radeon_device
> *rdev, unsigned offset, p = t / (PAGE_SIZE /
> RADEON_GPU_PAGE_SIZE); 
>  	for (i = 0; i < pages; i++, p++) {
> -		/* we reverted the patch using dma_addr in TTM
> for now but this
> -		 * code stops building on alpha so just comment
> it out for now */
> -		if (0) { /*dma_addr[i] != DMA_ERROR_CODE) */
> +		if (rdev->pdev, dma_addr[i] != 0) {

The same question for this condition.

-- 
Pekka Paalanen
http://www.iki.fi/pq/